[Haskell-cafe] trace output statements

[Tom Ellis]

I think forgetting about monads and just using do-notation will help you.

On Sun, Dec 23, 2018 at 04:44:57PM +0100, Damien Mattei wrote:
> i think learning Monads from scratch again will help me
> 
> On Sun, Dec 23, 2018 at 4:11 PM Tom Ellis <
> tom-lists-haskell-cafe-2017 at jaguarpaw.co.uk> wrote:
> 
> > Yes, exactly!
> >
> > On Sun, Dec 23, 2018 at 02:08:57PM +0100, Damien Mattei wrote:
> > > lazyness....?
> > >
> > > On Sun, Dec 23, 2018 at 8:40 AM Tom Ellis <
> > > tom-lists-haskell-cafe-2017 at jaguarpaw.co.uk> wrote:
> > >
> > > > On Sat, Dec 22, 2018 at 09:52:18AM +0100, Damien Mattei wrote:
> > > > > i have inserted trace statement that output variable
> > > > > ... i have strange behavior of output:
> > > >
> > > > Let's take a simpler example.  Do you understand why the trace
> > statments
> > > > from this small program appear in the order that they do?  (And for
> > what
> > > > it's worth I really think you'll be better off writing programs using
> > do
> > > > notation).
> > > >
> > > >
> > > > % cat test.hs
> > > > import Debug.Trace
> > > >
> > > > result =
> > > >   let a = trace "evaluating a" 2
> > > >       b = trace "evaluating b" 10
> > > >       c = trace "evaluating c" (a + b)
> > > >   in c
> > > > ~% ghci -e result test.hs
> > > > evaluating c
> > > > evaluating b
> > > > evaluating a
> > > > 12
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